#include <stdio.h>

#define ROWS 3
#define COLS 4

int sum2d(int rows, int cols, int ar[rows][cols]);

int main(void)
{
    int i, j;
    int rs = 3;
    int cs = 10;
    int junk[ROWS][COLS] = {
            {2,  4,  6, 8},
            {3,  5,  7, 9},
            {12, 10, 8, 6}
    };
    int morejunk[ROWS - 1][COLS + 2] = {
            {20, 30, 40, 50, 60, 70},
            {5,  6,  7,  8,  9,  10}
    };
    int varr[rs][cs]; // 变长数组（VLA）
    for (i = 0; i < rs; i++)
    {
        for (j = 0; j < cs; j++)
        {
            varr[i][j] = i * j + j;
        }
    }
    printf("3x5 array\n");
    printf("Sum of all elements = %d\n", sum2d(ROWS, COLS, junk));
    printf("2x6 array\n");
    printf("Sum of all elements = %d\n", sum2d(ROWS - 1, COLS + 2, morejunk));
    printf("3x10 VLA\n");
    printf("Sum of all elements = %d\n", sum2d(rs, cs, varr));
    return 0;
}

int sum2d(int rows, int cols, int ar[rows][cols])
{
    int tot = 0;
    for (int r = 0; r < rows; r++)
    {
        for (int c = 0; c < cols; c++)
        {
            tot += ar[r][c];
        }
    }
    return tot;
}
